DE602004011870T2 - Device and method for controlling the degree of superheating in a heat pump system - Google Patents

Description

Background of the invention

Field of the invention

The The present invention relates to an air conditioner and more particularly an apparatus and method for controlling the degree of superheating; that capable is a fluid compression to prevent a compressor.

Description of the Related Art

The Air conditioning is a device for regulating the temperature, the humidity, the air flow and the purity of air to make a pleasant To achieve indoor environment. Recently a multi-type air conditioning system has been developed which is capable several indoor units for to arrange each installation room and the air temperature for each To regulate the installation room.

A heat pump system make it possible, a combined cooling system and to use heating system by adding a refrigeration cycle principle to a refrigerant flow through a normal channel to let, and a heating circuit principle used to one refrigerant to flow in the opposite direction allow.

1 shows a general refrigeration cycle and its relation on the Mollier diagram. As in 1 is shown in a refrigeration cycle repeatedly compression → liquefaction → expansion → evaporation of a refrigerant is performed.

A compressor 10 Compresses an absorbed refrigerant and pushes superheated steam at high temperature and high pressure into an outdoor heat exchanger 15 out. This is the state of the refrigerant that comes from the compressor 10 is ejected into a gas state with a Mollier diagram. Overheat degree changed beyond the saturated state.

The outdoor heat exchanger 15 generates a phase change of the refrigerant to a liquid state by removing heat from the high-temperature, high-pressure refrigerant discharged from the compressor 10 is discharged, is exchanged with outside air. In doing so, the temperature of the refrigerant is rapidly lowered by being deprived of its heat by air passing through the outdoor heat exchanger 15 flows, and is discharged as a liquid state with a degree of supercooling.

Then regulates an expansion device 20 the refrigerant to a state in which easily evaporates in an indoor heat exchanger 25 takes place by the supercooled refrigerant at the outdoor heat exchanger 15 is decompressed.

Meanwhile, an indoor heat exchanger swaps 25 Heat of the refrigerant flowing to the expansion device 20 has been decompressed, with heat from an outside air. At this time, the temperature of the refrigerant is increased by absorbing heat from air passing through the indoor heat exchanger, thereby changing the phase of the refrigerant to a gas state.

In addition, the refrigerant goes out of the indoor heat exchanger 25 in the compressor 10 is absorbed into a gas state having a superheat degree (SH) which has evaporated beyond the saturated state.

From the above relation between the refrigeration cycle and the Mollier diagram is to be understood that the refrigerant through the compressor 10 , the outdoor heat exchanger 15 , the expansion device 20 , the indoor heat exchanger 25 flows and back to the compressor 10 goes.

In addition, the phase of the refrigerant during the process in which the refrigerant from the indoor heat exchanger 25 to the compressor 10 is changed, changed in the state of superheat degree. That is, the refrigerant that sorpt in the compres sor 10 is absorbed or removed from the compressor 10 is discharged should be completely in a gas state.

however the previous one is a theoretical result, and in general occurs in the application of the system to an actual product in a certain Extent Error on. If moreover a lot of the refrigerant, that in the cooling circuit flows, in comparison to the heat-exchanged condition relatively large or small is, is the phase change incomplete at every above process.

As a result of such a problem, that of the indoor heat exchanger 25 in the compressor 10 absorbed refrigerant may not have been completely phase-changed into the superheated vapor and still leak in the liquid state. When the refrigerant is accumulated in the liquid state in a collector (not shown) and then in the compressor 10 is absorbed, the noise is increased and the performance of the compressor is deteriorated.

In addition, in the heat pump system, when a heating mode is switched to a defrosting mode or a defrosting mode is switched to a heating mode, there is a great possibility that the refrigerant may leak in the heating mode liquid state in the compressor 10 is absorbed. Such a phenomenon occurs when the refrigerant flow changes during the mode switching process, when the heat exchanger having worked as the indoor heat exchanger functions as a condenser, and conversely, the heat exchanger operating as the outdoor heat exchanger functions as an evaporator.

In addition, the prior art air conditioner prevents the refrigerant in the liquid state from being excessively accumulated in the accumulator and being absorbed into the compressor by controlling the refrigerant flow amount using the expander 20 is regulated and achieved that the refrigerant that enters the compressor 10 is absorbed, has a degree of superheating. Here, the Expansionsvorrich device 20 a LEV (Linear Electronic Expansion Valve) or EEV (Electronic Expansion Valve), hereinafter referred to as EEV.

The Air conditioning according to the state However, the technique has the following problems.

If the refrigerant flow rate is controlled by controlling the expansion device so that the difference between the outlet temperature the compressor and the evaporation temperature of the outdoor heat exchanger while the switching process between the heating mode and the defrosting mode kept constant, the liquid refrigerant can enter the compressor flow, which is problematic.

For mode switching will namely the Switching performed by the four-way valve. If doing the compressor is operated simultaneously with the mode switching, is the circulation direction of the refrigerant vice versa, and the possibility that this liquid refrigerant is absorbed in the compressor is increased.

If hence the liquid refrigerant is absorbed into the compressor, a problem occurs that reliability of the product due to a deterioration in the performance of the compressor and noise generation is lowered.

If the outside temperature will be lowered as well the difference between the temperature of the outside air and the temperature of the outdoor heat exchanger diminished, reducing the heat exchange amount at the outdoor heat exchanger decreases and the accumulated in the collector liquid refrigerant increases and the possibility, that this liquid refrigerant in the compressor is absorbed, becomes large. Such a phenomenon acts as a factor that lowers the reliability of the heat pump system.

There Furthermore according to the state the technology the response of the system depending on a change from a degree of absorption temperature becomes very large, are very accurate for controlling the degree of absorption superheat Pressure sensor and temperature sensor required.

There Furthermore the temperature based on the highly saturated Pressure is calculated as a reference to control the Auslaßüberhitzungsgrades is used, the pressure at the low-pressure part and the refrigerant circulation amount are not considered, whereby an error increases, which is problematic.

JP 08014698 discloses an air conditioner where an overheat degree is calculated from a temperature difference between a condenser or evaporator outlet temperature and a saturation temperature, wherein an expansion valve is controlled among other things using the calculated superheat degree.

Summary of the invention

consequently The present invention is an apparatus and a method for controlling a superheat degree in a heat pump system This essentially causes one or more of the problems the restrictions and disadvantages of the prior art.

A The object of the present invention is a method for controlling a degree of overheating in a heat pump system to provide that makes it possible the existence Absorption super a compressor with a change an outside temperature changed becomes.

A Another object of the present invention is to provide a device and a method for controlling a degree of superheat in one heat pump system to provide an absorption superheat degree elevated is when an outside temperature falls to a low temperature.

Yet Another object of the present invention is to provide a device and a method for controlling a degree of superheat in one heat pump system to provide that capable is, an outlet superheat degree to control, for the Reference a calculated value of a reversible pressure is used calculated on the basis of low and high pressures of a compressor becomes.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and in part will be read in conjunction with It will be apparent to those skilled in the art upon evaluation of the following or may be learned from the practice of the invention. The objects and other advantages of the invention may be realized and obtained by the construction particularly pointed out in the written description and claims hereof as well as the appended drawings.

Around to solve these tasks and other advantages, and in accordance with the purpose of the invention, those embodied herein and generally described, a method of controlling a degree of superheat is described in a heat pump system provided.

The Method comprises: operating the heat pump system; Receive a low and a high pressure at a low pressure or a high pressure part a compressor, and an outlet temperature of the compressor; Calculating an absorption temperature of the compressor from a saturation temperature a refrigerant on a low pressure side, and calculating a reversible compression point from a result of a reversible compression process on one High pressure side using the calculated absorption temperature the compressor for a starting point; Calculating a current outlet superheat degree from a difference between a reversible compression temperature at a reversible compression point and the received outlet temperature the compressor; and controlling the system so that the current outlet superheat degree of the compressor can remain in a predetermined range.

In Another aspect of the present invention is a device for controlling a degree of superheating provided in a heat pump system. The device comprises: one or more indoor units; a or several outdoor units, each a compressor, a Kanalumschaltventil for selective Switching a channel of a refrigerant dependent from a cooling and a heating mode, an outdoor heat exchanger for exchanging Heat with an outside air and an outside EEV (Electronic Expansion Valve); a low and a High pressure sensor for determining a low or high pressure the compressor; an outlet tube temperature sensor for determining an outlet temperature the compressor; an absorption temperature detecting means for calculating an absorption temperature of the compressor below Use of a saturation temperature the refrigerant used and an absorption superheat degree from the determined low pressure value of the compressor; an outlet overheating degree determining means for Calculation of a reversible compression temperature by a reversible compression process and an outlet temperature on a high pressure side of the compressor from the absorption temperature the compressor, and calculating a current Auslaßüberhitzungsgrades; and a controller for comparing the current outlet superheat degree, by the outlet overheating degree determining means is calculated, with a Sollauslaßüberhitzungsgrad in advance then the plant is controlled so that the current Auslaßüberhitzungsgrad the target outlet superheat degree can follow.

The The present invention calculates the absorption temperature by: they the absorption superheat degree in terms of compensates for the saturation temperature, which is calculated from the low pressure sensor of the compressor, then in such a way controls that a Auslaßüberhitzungsgrad that the difference between the reversible compression temperature and the outlet temperature equivalent, can remain in a desired range, reducing the plant reliability is improved by a precise control.

It is understood that both the previous general description as well as the following Detailed description of the present invention by way of example and explanatory and intended to provide a further explanation of the invention, which is claimed.

Brief description of the drawings

The attached Drawings that are included to provide a more in-depth understanding of To provide invention, and incorporated in this application and form part of it, illustrate embodiment (s) The invention and serve together with the description, the Principle of the invention to explain. In the drawings show:

1 a structural view showing a duty cycle of the conventional air conditioner;

2 a structural view of a multi-type air conditioning system for controlling an absorption superheat degree according to a first embodiment of the present invention;

3 a structural view of a plant controller according to the first embodiment of the present invention;

4 a ph diagram for controlling an absorption superheat degree of the multi-type air conditioner according to the first embodiment of the present invention;

5 FIG. 12 is a graph showing the relationship between an outside temperature and a target absorption superheat degree according to the first embodiment of the present invention; FIG.

6 FIG. 10 is a flow chart showing a method of controlling an absorption superheat degree according to the first embodiment of the present invention; FIG.

7 a structural view of the multi-type air conditioning system for controlling a Auslaßüberhitzungsgrades according to a second embodiment of the present invention;

8th a block diagram for controlling an exhaust superheat degree according to the second embodiment of the present invention;

9 a ph diagram for controlling an outlet superheat degree according to the second embodiment of the present invention; and

10 FIG. 10 is a flowchart showing a method of controlling an exhaust superheat degree according to the second embodiment of the present invention.

Detailed description of the invention

It will now be described in detail on the preferred embodiments of the present invention Invention, examples of which are given in the accompanying drawings being represented.

It Now, an inventive method for controlling a degree of superheating will be described below in an air conditioner with reference to the accompanying drawings described.

First Embodiment

The 2 to 5 show a first embodiment of the present invention. In particular 2 13 is a structural view showing a multi-type air conditioner for use in both heating and cooling according to the first embodiment of the present invention.

Referring to 2 , are one or more outdoor units 111 and 111b , one or more indoor units 101 to 101n and a refrigerant pipe 109 provided, through which the refrigerant between the indoor unit and the outdoor unit can flow.

The indoor unit 101 to 101n has an indoor heat exchanger 103 and an indoor EEV 105 on. With the exterior of the indoor unit 101 to 101n is a refrigerant distributor 107 connected to the inlet and outlet of the refrigerant.

The indoor heat exchanger 103 selectively performs the cooling and heating for the interior by exchanging heat with an inside air by means of an indoor fan (not shown), operating as an evaporator in the cooling mode and operating as a condenser in the heating mode. The interior EEV 105 decompression expands the refrigerant that enters the indoor heat exchanger 103 flows.

In addition, the outdoor unit indicates 111 and 111b a compressor 113 , a channel switching valve 119 , an outdoor heat exchanger 121 and an outside EEV 123 on.

It depends on the load capacity of one or more compressors 113 for every outdoor unit 111 and 111b Install and compress absorbed high-pressure, high-pressure refrigerant and eject it. For the channel switching valve 119 In general, a four-way valve is used. The channel switching valve 119 switches the channel so that it is out of the compressor 113 discharged refrigerant according to the operation mode (the cooling mode or the heating mode) to the outdoor heat exchanger 121 or to the indoor heat exchanger 103 can flow.

Here is with the absorption side of the compressor 113 a collector 115 connected so that the refrigerant is a gaseous phase in the compressor 113 can be absorbed, and with the outlet side of the compressor 113 is an oil separator 117 (O / S) connected to the separation of oil. At the outlet side of the oil separator 117 is the channel switching valve 119 provided, and a capillary tube 116 is between the oil separator 117 and the collector 115 connected.

Also, depending on the load capacity of the compressor 113 several collectors 115 and oil separator 117 be installed.

The outdoor heat exchanger 121 exchanges heat with outside air by means of an outdoor fan (not shown), functioning as a condenser in the cooling mode and operating as an evaporator in the heating mode. The exterior EEV 123 decompression expands the refrigerant in the outdoor heat exchanger 121 flows.

On one side of the exterior EEV 123 is a holding tank 125 installed, and it is for connection to the exterior a main valve 127 between the outdoor unit 111 . 111b and the distributor 107 educated.

Meanwhile, are on an absorption side of the compressor 113 an absorption tube temperature sensor 133 and low pressure sensor 131 provided for measuring the temperature or the low pressure of the absorption tube. Here, the absorption tube temperature sensor 133 and the low pressure sensor 131 preferably on the refrigerant pipe in the absorption side of the collector 115 Installed.

Also, on the outlet side of the compressor 113 an outlet tube temperature sensor 137 and a high pressure sensor 135 installed for measuring the temperature or the high pressure of the outlet pipe. Here are the outlet tube temperature sensor 137 and the high pressure sensor 135 preferably between the oil separator 117 and the channel switching valve 119 Installed.

Moreover, within the installation space of the outdoor unit 111 respectively. 111b Outdoor temperature sensors 139 installed to measure an outside temperature.

When the multi-type air conditioner operates in the cooling mode, it flows through the compressor 113 compressed high-pressure, high-pressure refrigerant through the channel switching valve 119 in the outdoor heat exchanger 121 , The outdoor heat exchanger 121 The compressed high temperature, high pressure refrigerant condenses by heat exchange with outside air to a low temperature, high pressure state. The condensed refrigerant is passed through the inner EEV 105 decompression expanded and is passed through the indoor heat exchanger 103 heat exchanged with an indoor air, whereby the interior is cooled. Also, the refrigerant that passes through the indoor heat exchanger 103 has been evaporated, again in the compressor 113 absorbed, thereby operating in a refrigeration cycle.

When the multi-type air conditioner operates in the heating mode, this is done by the compressor 113 compressed high-pressure, high-pressure refrigerant through the channel switching valve 119 to the indoor heat exchanger 103 discharged to heat the interior by heat exchange with an indoor air. That through the indoor heat exchanger 103 condensed refrigerant is caused by an external EEV 123 decompression expanded and evaporated as a result of heat exchange with an outside air when passing through the outdoor heat exchanger 121 goes, and again to the compressor 113 which makes it work in a heating circuit.

As described above, it is possible the multi-type air conditioning system for use in both cooling and also to selectively control heating during heating or cooling the heating mode, and it is also possible to control the system, for one separate interior in cooling mode or the heating mode to work.

When the air conditioner is operating in the heating mode, the outdoor heat exchanger works 121 as an evaporator. When the outside temperature is low, the difference between the outdoor heat exchanger reduces 121 and the outside temperature, and a heat exchange amount at the outdoor heat exchanger 121 is reduced.

When the heat exchange quantity at the outdoor heat exchanger 121 reduces the amount of liquid refrigerant that accumulates in the collector 115 accumulates, which can cause damage to the compressor.

For this purpose, an absorption superheat degree (SH) control is performed to control the refrigerant flowing into the compressor 113 is absorbed in a state of overheating. The control of the absorption superheat degree (SH) is performed by adjusting an opening degree of the outer EEV 123 is regulated so that the refrigerant absorbed in the compressor can be absorbed in the gas state.

That is, when the outside temperature is lower than a predetermined temperature, the opening degree of the outside EEV becomes 123 is relatively reduced, and when the outside temperature is higher than a predetermined temperature, the opening degree of the outside EEV becomes 123 relatively increased.

3 is a block diagram for controlling the degree of superheat. As in 3 shown receives a control part 141 the actual absorption temperature and an outlet temperature, respectively, from the absorption tube and the outlet tube temperature sensors 133 and 137 , and receives the current low and high pressures, respectively, from the low and high pressure sensors 131 and 135 , In addition, the control part receives 141 the current outside temperature of the outside temperature sensor 139 ,

The control part calculates 141 the present absorption superheat degree (SH) using the absorption temperature and the low pressure, and calculates the current outlet superheat degree (SC) using the outlet temperature and the high pressure. That is, the absorption superheat degree is obtained as the difference between the saturation temperature of the refrigerant used at low pressure and the present absorption temperature, and the outlet superheat degree is obtained as the difference between the saturation temperature of the refrigerant used at high pressure and the present outlet temperature.

It also stores a data storage part 143 of the control part 141 a target absorption superheat degree and a target exhaust superheat degree for each operating condition and control data corresponding to an opening degree amount of the outer EEV 123 according to the degree of superheating.

The target absorption superheat degree (SH) is set differently depending on the outside temperature, that of the outside temperature sensor 139 Will be received. When the outside temperature drops to a low temperature, the target absorption superheat degree is set to a decreasing value.

4 Fig. 10 is a Mollier diagram for controlling the absorption superheat degree of the present invention. As in 4 are shown, a saturation point P1 and an absorption point 22 obtained of the refrigerant used at the low pressure point, which is determined by the low pressure sensor, and a saturation point 24 and an exhaust point P3 are obtained at the high pressure point detected by the high pressure sensor.

When the low pressure P _L and the saturation temperature T1 at the low pressure at the saturation point 21 , and the low pressure P _L and the present absorption temperature T2 at the absorption point P2 are obtained, the control part calculates 141 the absorption superheat degree ΔTs using a value obtained by subtracting the saturation temperature T1 from the current absorption temperature T2. In addition, the current outlet superheat degree ΔTd corresponds to a difference between the high-pressure refrigerant saturation temperature T4 and the current outlet temperature T3.

In addition, the control part controls 141 the plant so that the difference between the absorption temperature T2 of the compressor and the saturation temperature T1 of the refrigerant at the low pressure in a predetermined range can be arranged.

That is, when the present absorption superheat degree .DELTA.Ts is in accordance with the target absorption superheat degree set in advance, it is judged that the liquid refrigerant does not flow into the compressor, and if the current absorption superheat degree is not in accordance with the target absorption superheat degree, it is judged that the liquid Refrigerant may possibly flow into the compressor, and the degree of opening of the external EEV 123 is set. Therefore, the opening degree of the outer EEV becomes 123 set so that the absorption temperature of the compressor may be higher than a predetermined temperature, whereby the amount of refrigerant flowing into the outdoor heat exchanger is controlled.

The control part is doing this 141 the target absorption superheat degree taking into account variables such as a heat exchange amount of the outdoor heat exchanger, a temperature of the absorption pipe according to the outside temperature to a value by which the inflow of the liquid refrigerant can be prevented as much as possible.

Specifically, the target absorption superheat degree (SH) is set to a relatively increased value when the outside temperature Tao is low, as in FIG 5 and set to a relatively reduced value when the outside temperature is high. In addition, when the outside temperature is higher than a predetermined temperature, the target absorption superheat degree is fixed to a predetermined value.

When referring to 5 When the outside temperature Tao is lowered, the target absorption superheat degree (SH) is set to a relatively increased value, where the relation between the target absorption superheat degree (SH) and the outside temperature is as follows: SH1 (Tao1)> SH2 (Tao2)> SH3 ( Tao3)> SH4 (Tao4), since the minimum outside temperature is Tao1 and the minimum target absorption superheat degree is SH4.

The is called, when the outside temperature higher than Tao4, the relevant degree of superheat SH4, the minimum target absorption superheat degree is, and if the outside temperature higher than Tao3 is, the relevant superheat degree SH3, and when the outside temperature higher than Tao2 is the relevant degree of superheat SH2, and when the outside temperature higher than Tao1 is the relevant degree of superheat SH1.

in this connection Is it possible, the outside temperature of at a given temperature into several areas with one subdividing constant interval, and it is possible the Targeted absorption super-heating degree dependent from the outside temperature to set these values differently, such as the minimum Targeted absorption super-heating degree, who is capable the inflow of the liquid refrigerant to prevent the maximum target absorption superheat degree, and values, between the minimum and maximum target absorption superheat levels are arranged.

In addition, the outside temperature is inversely proportional to the target absorption superheat degree, and the target absorption superheat degree can not increase at a constant rate according to the lowering rate of the outside temperature. For example It is possible, depending on the environment, to set the temperature distribution between the outside temperatures Tao3 and Tao2 differently.

The opening degree of the external EEV 123 is increased or decreased depending on the outside temperature, so that such a target absorption superheat degree may be in accordance with the current absorption superheat degree.

When doing so, the opening degree of the outer EEV 123 is reduced, a flowing refrigerant amount is reduced, and the difference between a high pressure and a low pressure of the refrigerant is increased, and when the flowing refrigerant amount is reduced, the dryness of the refrigerant flowing out of the outdoor heat exchanger is increased. When the degree of dryness of the refrigerant at the outflow side of the outdoor heat exchanger is increased, an amount of the liquid refrigerant that accumulates in the collector is reduced. Consequently, the possibility that the liquid refrigerant flows into the compressor is remarkably reduced. At this time, the current absorption superheat degree is smaller than the target absorption superheat degree.

In addition, when the current absorption superheat degree is larger than the target absorption superheat degree, the opening degree of the outer EEV becomes 123 increases, whereby the current absorption superheat degree follows the target absorption superheat degree and reaches the target value.

Of the Targeted absorption super-heating degree takes for every outside temperature band a value corresponding to the regulated value of the opening degree of the outer EEV matches as much as possible to prevent that liquid refrigerant due to the outside temperature is accumulated in the collector.

6 FIG. 10 is a flowchart showing a method of controlling a superheat degree according to the first embodiment of the present invention. FIG.

When referring to 6 the heat pump system starts to operate (S101), the system receives an absorption temperature from the absorption tube temperature sensor of the compressor, a low pressure from the low pressure sensor, and the current outside temperature from the outside temperature sensor (S103).

there becomes the preset target absorption superheat degree according to the current outside temperature calculated by the outside temperature sensor is determined (S105).

In addition, will using the difference between the absorption pressure saturation temperature the compressor and the absorption tube temperature the current absorption superheat degree calculated (S107). After that he will open the external EEV adjusted so that the above calculated current Absorption super in accordance with the target absorption superheat degree can stand (S109).

Of the Sequence of S109 is performed in the following manner, in the: when the opening degree of Outdoor EEV is reduced, the refrigerant flow rate is reduced and that associated with the external EEV Outdoor heat exchanger Heat with respect to Refrigerant charge which comparatively reduces is, and the degree of dryness may be elevated will, so that the condition of the refrigerant changes into a gas state. Consequently, flows the refrigerant, that through the outdoor heat exchanger was sent through the channel switching valve in the collector, thereby the liquid Refrigerant which is accumulated in the collector is reduced. If therefore the outside temperature is low, it is possible the plant reliability during operation of the heat pump to significantly improve in the heating mode.

The above-described first embodiment regulates the opening degree of the Foreign EEV using a low pressure, an absorption temperature, an outside temperature, the absorption superheat degree variables are so that the current absorption superheat degree, the difference between the saturation temperature the refrigerant used, which is calculated from the low pressure value measured above, and the temperature of the refrigerant that is absorbed into the compressor, the target absorption superheat degree can follow that depends from the outside temperature changed becomes.

Second Embodiment

The 7 to 10 show the second embodiment of the present invention.

The second embodiment of the present invention is a method for controlling an exhaust superheat degree, and the same reference numerals are used for the same parts as in the multi-type air conditioner for use in both cooling and heating, which are shown in FIG 2 will be shown. The difference is that the second embodiment of the present invention does not use the absorption tube temperature sensor, but controls an outlet superheat degree.

Referring to the 7 and 8th , is on the absorption side of the compressor 113 a low pressure sensor 131 provided, and on the Outlet side of the compressor 113 are a high pressure sensor 135 or an outlet tube temperature sensor 137 intended.

In addition, the control part receives 141 a low pressure P _L passing through the low pressure sensor 131 a high pressure is detected by the high pressure sensor 135 is determined, and an outlet temperature of the compressor 113 from the exhaust pipe temperature sensor 137 ,

Here, the control part 141 an absorption temperature detecting part 145 and an outlet overheat degree determination part 147 on. The absorption temperature detecting part 145 calculates a saturation temperature of the refrigerant used from the low pressure value of the compressor, that of the low pressure sensor 131 is received, and determines the absorption temperature of the compressor 113 by adding the saturation temperature to the absorption superheat degree stored in a data storage part 143 is stored.

In addition, the exhaust overheat degree determination part detects 147 by the reversible compression process, the outlet superheat degree as the difference between a temperature at a reversible compression point and an outlet temperature received from the exhaust pipe temperature sensor from the position of the absorption temperature passing through the absorption temperature detection part 145 is determined.

As in 9 shown calculates the absorption temperature detecting part 145 a saturation temperature T1 of the refrigerant used by using a low pressure passing through the low pressure sensor 131 is detected, and measures the absorption temperature T2 at the low pressure by adding a predetermined absorption superheat degree .DELTA.Ts to the above-calculated saturation temperature T1 of the refrigerant. At this time, it is possible to calculate an absorption point (P2: P _L , T2) on the ph diagram of the refrigerant used by using the absorption temperature and the low pressure.

Here, the absorption temperature T2 is obtained by summing the absorption superheat degree ΔTs and the saturation temperature of the refrigerant. At this time, the absorption superheat degree becomes in the data storage part 143 is stored as a temperature value higher than the saturation temperature of the refrigerant on the low pressure side by as much as a predetermined temperature.

And it is possible, a reversible compression point 25 , which is a result of the reversible compression process, from the absorption point 22 to calculate. At this time, since the compression process of the actual compressor is the irreversible compression process (isentropic efficiency <1.0), not the isentropic process which is the reversible compression process, the irreversible compression point becomes 23 whose position is higher than the reversible compression point 25 is, an outlet point of the compressor.

The outlet point of the compressor 113 can be determined by the use of the current outlet temperature T3 passing through the outlet tube temperature sensor 137 is determined, and the high pressure PH calculated, and the irreversible compression point 23 of the compressor 113 is determined.

In addition, the reversible compression point 25 is obtained by the reversible compression process from the absorption point P2 obtained from the saturation temperature of the compressor and the absorption superheat degree, and the exhaust superheat degree ΔTd of the compressor becomes by using the difference between the saturation temperature T3s at the reversible compression point 25 and the current outlet temperature T3 of the compressor. Thus, the outlet superheat degree ΔTd becomes the reference for control.

As described above, the exhaust superheat degree ΔTd is controlled by the use of a condition to keep the refrigerant absorbed in the supercharger in the overheat condition. For this purpose, the external EEV 123 (or the outdoor fan) is controlled so that the difference between the temperature T3s of the reversible compression point P3 of the compressor and the outlet temperature T3 of the compressor corresponding to the irreversible compression point P4 can be arranged in a predetermined range. Therefore, a control can be performed in which both information of the high-pressure part and the low-pressure part of the compressor are all included.

According to the prior art, when the discharge super-heating degree ΔTd_old of the compressor is controlled, the high-pressure side of the compressor performs control by taking the difference between the saturated temperature T4 of the refrigerant used and the discharge temperature T3 of the refrigerant discharged from the compressor as the outlet super-heating degree ΔTd_old is defined, however, such exhaust outlet degree control is performed by using the temperature as a reference calculated from the saturated pressure at high pressure, therefore, the control is performed without considering the pressure of the low pressure part and the circulating refrigerant amount, whereby a large error in controlling a degree of overheating occurs.

The preceding second embodiment controls the outlet superheat degree based on a calculated value of the reversible compression, by the use of the pressures the low-pressure and high-pressure parts are obtained on the duty cycle, where the saturation temperature at the low pressure part, the saturation temperature on the high pressure side and the outlet temperature of the compressor used, which compared to a case of controlling the absorption superheat degree using the sensor (temperature sensor) of the same accuracy possibly a more precise control performed will and the plant reliability is improved.

Also controls the second embodiment the present invention, the Auslaßüberhitzungsgrad, wherein as Reference the difference between the saturation temperature at the reversible compression point in the low-pressure part of the compressor and the current outlet temperature, not the saturation temperature used at high pressure, possibly providing more accurate control the Auslaßüberhitzungsgrades carried out becomes.

10 shows a method for controlling the Auslaßheat degree of the compressor according to the second embodiment of the present invention.

When referring to 10 the heat pump system starts to operate (S111), the system receives a low and high pressure from the low and high pressure sensors of the compressor, respectively, and receives an outlet temperature of the compressor from the exhaust pipe temperature sensor (S113).

there becomes the saturation temperature the refrigerant used calculated from the low pressure value measured above, and the absorption point on the p-h diagram is determined by an addition of a given Absorption super-heating degree to the above calculated saturation temperature the low pressure side is calculated (S115, S117). This is the absorption point of the compressor by using the low pressure and the absorption temperature receive.

In addition, will the reversible compression temperature through the reversible compression process the use of the absorption point of the compressor for the reference calculated, and the reversible compression point is determined by the use the reversible compression temperature and the high pressure of the compressor received (S119). Here, the reversible compression point is off the reversible compression temperature and the high pressure.

After that becomes the present one discharging super from the difference of the reversible compression temperature at the reversible Compression point and the outlet temperature of the compressor (S121), and the obtained current Auslaßüberhitzungsgrad becomes with the target outlet superheat degree compared, then the plant is controlled so that the current Auslaßüberhitzungsgrad in the range of Sollauslaßüberhitzungsgrads can fall (S123). It is made clear that such a method is overheating control that is different from the Auslaßüberhitzungsgradsteuerung of the prior art, which distinguishes the difference between the saturation temperature used at high pressure and the outlet temperature.

Therefore becomes the opening degree of the Foreign EEV controlled so that the current discharging super fall into the target range. That is, when the current outlet superheat degree smaller than the target outlet superheat degree range is, the opening degree becomes of the Foreign EEV reduced, and if the present discharging super greater than the target outlet superheat degree range is, the opening degree becomes the external EEV elevated, thereby reducing the plant reliability in comparison with the case of controlling the absorption superheat degree can be improved.

meanwhile may be another embodiment of the present invention simultaneously or selectively the degree of absorption superheat and the outlet superheat degree control using the first and second embodiments. That is, it is based on the absorption and the Auslaßüberhitzungsgrads possible, the current Absorption super to steer so that he the target absorption superheat degree for each Outside temperature band follows, and the present discharging super, the temperature difference between the reversible and the irreversible Processes is to be controlled so that it is the target outlet superheat degree follows. It may be possible be, the opening degree the exterior EEV on the area which regulates both the target absorption and target outlet superheat levels Fulfills, when the absorption and discharge super-heating levels are controlled.

According to a method for controlling the superheat degree in the heat pump system of the present invention, the target absorption superheat degree is set according to the outside temperature so that the state change of the refrigerant compensates depending on the outside temperature can be, and the system is controlled so that the current absorption superheat degree can follow the preset target absorption superheat degree depending on the outside temperature, whereby the inflow of the liquid refrigerant is minimized in the compressor.

Also controls the present invention the Auslaßüberhitzungsgrad that the difference between the temperature of the reversible compression process and the outlet temperature corresponds, so that he remains in the desired range after the absorption temperature has been calculated, by the absorption superheat degree in terms of the saturation temperature which is compensated from the low pressure sensor of the compressor which reduces system reliability by providing accurate Control is improved.

It will be clear to experts that different Modifications and variations are made in the present invention can be without leaving the spirit or framework of the inventions. consequently It is intended that the The present invention provides the modifications and variations of this invention provided they fall within the scope of the appended claims.

Claims (14)

A method for controlling a degree of superheat in a heat pump plant, the method comprising: operating the heat pump plant; Receiving a low and a high pressure (P _L, P _H) at a low pressure or a high-pressure part of a compressor ( 113 ), and an outlet temperature (T3) of the compressor ( 113 ); Calculating an absorption temperature (T2) of the compressor (T2) 113 ) from a saturation temperature (T1) of a refrigerant on a low pressure side, and calculating a reversible compression point (P5) from a result of a reversible compression process on a high pressure side using the calculated absorption temperature (T2) of the compressor ( 113 ) for a starting point; Calculating a present outlet superheat degree (ΔTd) from a difference between a reversible compression temperature (T3s) at a reversible compression point (P5) and the received outlet temperature (T3) of the compressor (T3) 113 ); and controlling the system so that the current outlet superheat degree (ΔTd) of the compressor ( 113 ) can remain within a given range. Method according to claim 1, wherein the absorption temperature (T2) of the compressor (T2) 113 ) on the low pressure side by calculating a saturation temperature (T1) of the refrigerant from a low pressure sensor (FIG. 131 ) of the compressor ( 113 ) and adding an absorption superheat degree (ΔTs) to the calculated saturation temperature (T1) of the refrigerant. A method according to claim 2, wherein the absorption superheat degree (ΔTs) is a value satisfying a condition to match that at the compressor (ΔTs). 113 ) to keep absorbed refrigerant in an overheating state. The method of claim 2, wherein the degree of absorption superheat (ΔTs) a value is set that is inversely proportional to a outside temperature is. Method according to claim 1, wherein when the absorption temperature (T2) of the compressor (T2) 113 ), a reversible compression process is performed with the use of a position of the refrigerant used on a ph diagram for a starting point, so that the reversible compression point ( 25 ) on the high pressure side and the reversible compression temperature (T3s) at that point. A method according to claim 1, wherein, when the present high-pressure-side outlet super-heating degree (ΔTd) is not in a predetermined range, an opening degree of an outer-EEV (Electronic Expansion Valve) ( 123 ) is set. The method of claim 5, wherein when the current outlet superheat degree (ΔTd) is smaller than a predetermined target area, an opening degree of an external EEV ( 123 ), and when the current outlet superheat degree (ΔTd) is larger than a predetermined target area, the opening degree of the outer EEV ( 123 ) is increased. Method according to claim 1, wherein for controlling the outlet super-heating degree (ΔTd) of the compressor ( 113 ) Data can be used by an absorption sensor on the low-pressure side of the compressor ( 113 ), a high pressure sensor ( 135 ) on a high pressure side of the compressor ( 113 ) and an outlet tube temperature sensor ( 137 ) are received. Device for controlling a degree of superheating in a heat pump system, the device comprising: one or more indoor units ( 101 ); one or more outdoor units ( 11a . 111b ), each one a compressor ( 113 ), a channel switching valve ( 119 ) for selectively switching a channel of a refrigerant depending on a cooling and a Heating mode, an outdoor heat exchanger ( 121 ) for exchanging heat with an outside air and an external EEV (electronic expansion valve) ( 123 ) exhibit; a low and a high pressure sensor ( 131 . 135 ) for determining a low or a high pressure (P _L , P _H ) of the compressor ( 113 ); an outlet tube temperature sensor ( 137 ) for determining an outlet temperature of the compressor ( 113 ); an absorption temperature determination device ( 145 ) for calculating an absorption temperature (T2) of the compressor ( 113 ) using a saturation temperature (T1) of the refrigerant used and an absorption superheat degree (ΔTs) from the determined low-pressure value of the compressor ( 113 ); an outlet overheating degree determining device ( 147 ) for calculating a reversible compression temperature (T3s) by a reversible compression process and an outlet temperature (T3) on a high pressure side of the compressor (T3s) 113 ) from the absorption temperature (T2) of the compressor (T2) 113 ), and calculating a current outlet superheat degree (ΔTd); and a control device ( 141 ) for comparing the current outlet superheat degree (ΔTd) obtained by the outlet superheat degree determining means (Fig. 147 ) is calculated with a target outlet superheat degree (ΔTd) set in advance, and then the plant is controlled so that the current outlet superheat degree (ΔTd) can follow the target outlet superheat degree. Device according to claim 9, wherein the control device ( 141 ) an opening degree of the outer EEV (electronic expansion valve) ( 123 ) is set so that the current outlet superheat degree (ΔTd) can be in accordance with the target outlet superheat degree (ΔTd). Apparatus according to claim 10, wherein the control device ( 141 ) the degree of opening of the external EEV ( 123 ) when the current exhaust superheat degree (ΔTd) is smaller than the target exhaust superheat degree (ΔTd), and the opening degree of the outer EEV ( 123 ) increases when the current outlet superheat degree (ΔTd) is greater than the target outlet superheat degree (ΔTd). Apparatus according to claim 9, wherein the absorption superheat degree (ΔTs) is set high when an outdoor temperature is low. Device according to claim 9, wherein the control device ( 141 ) an opening degree of an outer EEV (Electronic Expansion Valve) ( 123 ), when the outside temperature is low, and the opening degree of the outside EEV ( 123 ) increases when the outside temperature is high. Device according to claim 9, wherein the control device ( 141 ) an opening degree of an outer EEV (Electronic Expansion Valve) ( 123 ) in a range satisfying both the absorption superheat degree (ΔTs) and the exhaust superheat degree (ΔTd).